It was not the biggest or the most valuable painting in the Louvre - a diminutive landscape by Corot - but it was gone and an embarrassed museum wanted it back. All entrances to the sprawling building were blocked by police for nearly three hours.
Frightening rumours circulated among the large crowd trapped inside: there had been a murder, a bomb, a fire. People fainted, screamed, shouted. But the police insisted on searching the art-lovers' bags - and some of the art-lovers' bodies - one by one.
The tiny 13in-by-19in canvas by the French, pre-Impressionist painter Camille Corot was sliced out of its frame in an obscure, little-visited and unguarded room in the Sully pavilion. Its absence was noticed by an attendant at 1.30pm on Sunday. It was still missing yesterday.
Five Corots were stolen from French museums - allegedly for Japanese collectors - in the 1980s; all were later recovered.
This is the fourth incident of the kind at the Louvre in the last four years. A religious robe from the 4th-century BC disappeared from the collection of ancient Greek artefacts this January; two relatively obscure paintings vanished in 1995 and 1994. There have also been several acts of vandalism.
The attacks have mostly occurred on a Sunday when the museum is most crowded. On each occasion, the Louvre has promised to review its security. Pierre Rosenberg, president-director of the museum, admitted yesterday that the stolen Corot had no individual alarm; it was hung in a room with no permanent attendant and no video surveillance. The thief prised open a glass security case and cut around the painting with a razor, without being noticed.
Mr Rosenberg tried to be philosophical yesterday. "In my opinion, thefts of this kind are relatively rare. They are part of our sad fate [as one of the most visited art galleries in the world]."
The museum was not so relaxed when the theft was discovered. Visitors complained that they had been squashed for two hours as bags were laboriously checked. No audible explanation was given. Louvre staff explained that they had been asking for a proper system of loudspeakers for years: the authorities had always refused, fearing it would make the place appear "like a supermarket".
The missing canvas - Le Chemin de Sevres - was painted in 1858-9. Corot paintings fluctuate wildly in price - from pounds 400 to pounds 600,000 - according to their size and subject. A Corot of a similar size and topic was sold recently in New York for just over pounds 70,000.